Climatological Report (Monthly)
Issued by NWS

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CXUS53 KGRR 021721 CCA
CLMJXN

CLIMATE REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS, MI
916 AM EST SUN JAN 1 2017

...................................

...THE JACKSON MI CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2016...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1944 TO 9999

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
HIGHEST            56   12/26        MM      MM       62  12/12
LOWEST              0   12/19        MM      MM       20  12/20
AVG. MAXIMUM     32.5              34.7    -2.2     46.3
AVG. MINIMUM     21.8              21.5     0.3     33.4
MEAN             27.1              28.1    -1.0     39.8
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32     13              12.6     0.4        4
DAYS MIN <= 32     25              26.5    -1.5       18
DAYS MIN <= 0       1               1.1    -0.1        0

PRECIPITATION (INCHES)
TOTALS           0.88              1.87   -0.99     2.31
DAILY AVG.       0.03              0.06   -0.03     0.07
DAYS >= .01        13              12.4     0.6       12
DAYS >= .10         3               5.2    -2.2        5
DAYS >= .50         0               0.8    -0.8        2
DAYS >= 1.00        0               0.1    -0.1        0
GREATEST
 24 HR. TOTAL    0.37   12/25 TO 12/26

DEGREE_DAYS
HEATING TOTAL    1165              1144      21      772
 SINCE 7/1       2135              2548    -413     1893
COOLING TOTAL       0                 0       0        0
 SINCE 1/1        829               592     237      540
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              10.8
RESULTANT WIND SPEED/DIRECTION   7/241
HIGHEST WIND SPEED/DIRECTION    38/230    DATE  12/20
HIGHEST GUST SPEED/DIRECTION    48/230    DATE  12/20

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.80
NUMBER OF DAYS FAIR            3
NUMBER OF DAYS PC              9
NUMBER OF DAYS CLOUDY         19

AVERAGE RH (PERCENT)     74

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       1
LIGHT RAIN                6     FREEZING RAIN              0
LT FREEZING RAIN          1     HAIL                       0
HEAVY SNOW                5     SNOW                       6
LIGHT SNOW               19     SLEET                      0
FOG                      18     FOG W/VIS <= 1/4 MILE      3
HAZE                     11

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

&&

NOTE... PRECIPITATION AMOUNTS DURING HEAVY SNOW ARE
UNDERREPRESENTED BY THE JACKSON ASOS.

DECEMBER 2016 FEATURED A VARIETY OF WEATHER DURING THE MONTH AND
ACROSS THE AREA OF CENTRAL TO SOUTHWEST LOWER MICHIGAN. AVERAGED
OUT... THE MONTH WAS NEAR TO A LITTLE BELOW NORMAL IN TERMS OF
TEMPERATURE... THE COOLEST MONTH RELATIVE TO NORMAL SINCE APRIL.
LIQUID/MELTED PRECIPITATION WAS NEAR TO A LITTLE BELOW NORMAL... AND
SNOW TOTALS RANGED FROM A LITTLE BELOW TO WELL ABOVE NORMAL. DIRECT
SUNSHINE WAS MEASURED AT 9 PERCENT OF POSSIBLE IN GRAND RAPIDS...
BELOW THE DECEMBER AVERAGE OF 20 PERCENT AND ONLY SLIGHTLY SUNNIER
THAN SOME OF THE CLOUDIEST MONTHS ON RECORD.

THE FIRST WEEK OF THE MONTH HAD SLIGHTLY WARMER THAN NORMAL
TEMPERATURES AND PRODUCED SNOW ACCUMULATIONS BETWEEN 1 AND 5 INCHES
ON DECEMBER 4TH. FOR MANY IN SOUTHWEST MICHIGAN IT WAS THE FIRST
SUBSTANTIAL ACCUMULATION OF THE COLD SEASON.

STARTING THE SECOND WEEK OF THE MONTH... ARCTIC AIR MASSES PLUNGED
INTO THE REGION AND REMAINED UNTIL DECEMBER 20TH. CERTAINLY THE
COLDEST DECEMBER AIR SINCE 2013 BUT BY SOME MEASURES SINCE 2004...
HIGH TEMPERATURES AWAY FROM LAKE MICHIGAN TOPPED OUT IN THE TEENS
FOR A FEW OF THOSE DAYS... AND LOWS OCCASIONALLY DIPPED NEAR TO
BELOW ZERO. COUPLED WITH THE WARMEST LAKE MICHIGAN WATER
TEMPERATURES ON RECORD SINCE THE 1980S... LAKE EFFECT SNOW WAS
COMMON FOR THOSE TWO WEEKS... THOUGH THE GREATEST AMOUNTS SKIPPED
OVER MUSKEGON AND FELL A BIT FARTHER INLAND. A LOW PRESSURE SYSTEM
THAT TAPPED INTO SOUTHERN U.S. MOISTURE ALSO PRODUCED 5 TO 10 INCHES
OF SNOW ACROSS THE WHOLE AREA ON DECEMBER 11TH.

RELATIVELY MILD AIR REPLACED THE SHARP COLD AFTER THE 20TH. RAIN AND
ISOLATED THUNDERSTORMS LATE ON THE 25TH INTO THE 26TH... PLUS RECORD
WARM TEMPERATURES IN THE 50S ON THE 26TH... MELTED MOST OF THE
AREA`S SNOWPACK. DESPITE THE SOMEWHAT WARMER THAN NORMAL AIR AT THE
END OF THE MONTH... LAKE EFFECT SNOW FOCUSED ON SOUTHWEST MICHIGAN
ON THE 29TH DROPPED 4 TO 6 INCHES BETWEEN SOUTH HAVEN AND KALAMAZOO.

$$

CAS



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